1. Field of the Invention
This invention relates to the pyrochemical processing of nuclear waste products. It particularly relates to the achieving of high efficiencies in the electroseparation of actinide and rare earth metals.
2. Background Information
A pyrochemical process has been proposed to recover 99% of the remaining transuranium (TRU) materials (Np, Pu, Am, Cm) from plutonium-uranium extraction (PUREX) waste to simplify nuclear waste management and reduce the cost involved. The high-level PUREX nuclear waste is separated into a TRU-rich stream and a TRU-depleted stream. The TRU-rich stream could be stored indefinitely or, if sufficiently pure, could be fissioned in a fast reactor or accelerator or similar device to thereby convert a large fraction of the waste to a low-TRU high-level waste (HLW). After storage of the depleted TRU HLW for a period of time to allow the fission products to decay to low levels, this waste could be disposed of as low-level waste (LLW) thus substantially reducing disposal costs compared to those involving TRU-rich waste.
Many processes have been proposed for reprocessing and separating spent nuclear fuels. See for example, U.S. Pat. Nos. 4,399,108, 4,880,506, and 4,892,684. In U.S. Pat. No. 5,041,193, a pyrochemical process is utilized for recovering actinide metals from spent nuclear fuel oxides. This pyrochemical process includes electrorefining the metal complex from an anode by electrolytically oxidizing actinides into a salt and electrodepositing actinides onto a cathode to form an actinide metal deposit. The actinide metal deposit is then melted to separate the salts and the actinide metals.
In order to achieve the desired economies in the use or disposal of the nuclear waste products, it is essential that high efficiencies be achieved in the electrochemical separation of actinide and rare earth metals as part of the pyrochemical process.
It is, therefore, an object of the present invention to provide an improved electrochemical process utilizing a molten salt electrolyte for the more complete electroseparation of actinide and rare earth elements.
It is a further object to provide an improved electrochemical process which may be utilized in conjunction with other chemical or electrochemical processing steps to further enhance such more complete electroseparation.